Offset passive valve for vehicle exhaust system

ABSTRACT

An exhaust component includes a wall with an inner surface defining an exhaust gas flow path. A passive valve assembly includes a vane that is positioned within the exhaust gas flow path to be pivotable between open and closed positions. The vane is defined by a plane that extends across a width of the vane. The vane is supported by a shaft that defines an axis of rotation. The axis of rotation is offset from the plane of the vane such that the vane can be pivoted to a fully open position without interfering with the inner surface of the wall.

RELATED APPLICATIONS

This application claims priority to provisional application No. 60/989,508 filed on Nov. 21, 2007.

TECHNICAL FIELD

The subject invention relates to an offset passive valve in a vehicle exhaust system.

BACKGROUND OF THE INVENTION

Exhaust systems are widely known and used with combustion engines. Typically, an exhaust system includes exhaust tubes that convey hot exhaust gases from the engine to other exhaust system components, such as mufflers, resonators, etc. Mufflers and resonators include acoustic chambers that cancel out sound waves carried by the exhaust gases. Although effective, these components are often relatively large in size and provide limited nose attenuation.

Passive valves have been used in a muffler to provide further noise attenuation. However, the proposed valves have numerous drawbacks that limit their widespread use in a variety of applications. One disadvantage with passive valves is their limited use in high temperature conditions. Another disadvantage with known passive valve configurations is that these valves do not effectively attenuate low frequency noise.

Attempts have been made to improve low frequency noise attenuation by increasing muffler volume or increasing backpressure. Increasing muffler volume is disadvantageous from a cost, material, and packaging space perspective. Increasing backpressure can adversely affect engine power. Thus, solutions are needed to more effectively incorporate passive valves within an overall exhaust system.

When the passive valve is used within an exhaust pipe, such as a pipe in a muffler or when used in a by-pass pipe configuration, challenges are presented when the passive valve is moved toward a fully open position. The passive valve includes a flapper valve body or vane that is positioned within the exhaust pipe, with the vane being pivotable between open and closed positions. The passive valve is spring biased toward the closed position, and when exhaust gas pressure is sufficient to overcome this spring bias, the vane is pivoted toward the open position. In by-pass configurations, the vane provides 100% coverage, i.e. complete blockage, of the exhaust component when in the closed position. When closed, exhaust gases can flow outside of the exhaust pipe that houses the vane via a by-pass pipe that is connected to the exhaust pipe at locations upstream and downstream of the vane.

When the vane is moved toward the fully open position potential interference challenges are presented by the shape of the pipe itself. Traditionally, the vane has been supported by a shaft mounted to a wall of the pipe, with the shaft defining a pivot axis of rotation that is aligned with the vane, i.e. a plane defined by the vane intersects the pivot axis of rotation. The pipe typically includes a curved pipe wall having an inner surface that defines the exhaust gas flow path. When the vane is pivoted near this wall surface of the pipe, an opening angle for the passive valve is limited by the width of the vane and the curvature of the wall. Limiting the opening angle is disadvantageous from a back pressure standpoint, in addition to failing to achieve a true fully open position for maximum flow.

Therefore, there is a need to provide a passive valve arrangement that can achieve a fully open position by maximizing the opening angle to achieve minimum backpressure penalties. This invention addresses those needs while avoiding the shortcomings and drawbacks of the prior art.

SUMMARY OF THE INVENTION

An exhaust component includes a wall with an inner surface defining an exhaust gas flow path. A passive valve assembly includes a vane that is positioned within the exhaust gas flow path to be pivotable between open and closed positions. The vane is defined by a plane that extends across a width of the vane. The vane is supported by a shaft that defines an axis of rotation. The axis of rotation is offset from the plane of the vane.

In one example, the exhaust component comprises a pipe having a curved inner wall surface. A housing is mounted to a curved outer surface of the pipe. At least one bushing is mounted within the housing to pivotally support the shaft. A resilient member biases the vane toward the closed position, and the vane is pivoted from the closed position towards the open position in response to an exhaust gas flow that exceeds a biasing force of the resilient member.

In one example, the plane and the axis of rotation have a non-intersecting relationship and a connecting arm is used to maintain a spaced relationship between the plane and the axis of rotation. The connecting arm has one portion coupled to the shaft and another portion coupled to the vane. The connecting arm extends transversely to the plane and to the axis of rotation.

In one example, the vane comprises a disc-shaped body having a greater width than thickness. The plane is defined across the width of the disc-shaped body.

By offsetting the plane from the vane, the vane can be pivoted to a fully open position to maximize flow without interfering with a curved inner surface of the wall of the pipe. These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of one example of an exhaust pipe component and passive valve assembly.

FIG. 2 shows a side view of an exhaust component with an offset vane.

FIG. 3 is a schematic side view of the exhaust component of FIG. 2 in a fully open position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As shown in FIG. 1, an exhaust component, such as an exhaust tube or pipe 10 includes an exhaust throttling valve, referred to as a passive valve assembly 12. The passive valve assembly 12 is movable between an open position where there is minimal blockage of an exhaust gas flow path 16 and a closed position where a substantial portion of the exhaust gas flow path 16 is blocked. The passive valve assembly 12 is resiliently biased toward the closed position and is moved toward the open position when exhaust gas flow generates a pressure sufficient enough to overcome the biasing force.

In the example shown, the exhaust pipe 10 comprises a single pipe body 14 that defines the exhaust gas flow path 16. In one example, the pipe body 14 includes a curved outer surface 14 a and a curved inner surface 14 b that defines the exhaust gas flow path 16. In one example, the pipe body 14 has a circular cross-section.

The passive valve assembly 12 includes a valve body or vane 18 that blocks a portion of the exhaust gas flow path 16 when in the closed position. As discussed above, the vane 18 is pivoted toward the open position to minimize blockage of the exhaust gas flow path 16 in response to pressure exerted against the vane 18 by exhaust gases.

In one example, the vane 18 is fixed to a shaft 20 with a connecting arm, shown schematically at 22 in FIG. 1. A slot 24 is formed within the curved outer surface 14 a of the pipe body 14. A housing 26, shown in this example as a square metal structure, is received within this slot 24 and is welded to the pipe body 14. Other housing configurations could also be used. The shaft 20 is rotatably supported within the housing 26 by first 28 and second 30 bushings or bearings and defines an axis of rotation A.

The first bushing 28 is positioned generally at a first shaft end 32. The first bushing 28 comprises a sealed interface for the first shaft end 32. The shaft 20 includes a shaft body 34 that has a first collar 36 and a second collar 38. The first bushing 28 includes a first bore that receives the first shaft end 32 such that the first collar 36 abuts directly against an end face of the first bushing 28 to provide a sealed interface. As such, exhaust gases cannot leak out of the first bushing 28 along a path between the shaft 20 and first bushing 28.

The second bushing 30 includes a second bore through which the shaft body 34 extends to a second shaft end 40. The second collar 38 is located axially inboard of the second bushing 30. The shaft 20 extends through the second bore to an axially outboard position relative to the second bushing 30. A resilient member, such as a spring 42 for example, is coupled to the second shaft end 40 with a spring retainer 44. The spring retainer 44 includes a first retainer piece 46 that is fixed to the housing 26 and a second retainer piece 48 that is fixed to the second shaft end 40. One spring end 50 is associated with housing 26 via the first retainer piece 46 and a second spring end (not viewable in FIG. 1 due to the spring retainer 44) is associated with the shaft 20 via the second retainer piece 48.

The vane 18 comprises a disc-shaped body 60 that is generally flat, and which has a significantly greater width W (FIG. 1) or diameter than a thickness t (FIG. 2) of the disc-shaped body 60. The vane 18 defines a plane (a vane center plane) P (FIG. 2) that extends across the width W of the disc-shaped body 60. It should be noted that the thickness t of the disc-shaped body 60 is exaggerated in FIG. 2 to clearly show the plane P.

As shown in FIG. 2, the plane P is offset from the axis of rotation A by a distance D. This distance D remains generally constant as the vane 18 is pivoted between the open and closed positions, and as such, the plane P and the axis of rotation A have a non-intersecting relationship. By offsetting the plane P from the vane 18, the vane 18 can be pivoted to a fully open position as shown in FIG. 3 without interfering with the curved inner surface 14 b of a wall of the pipe body 14.

As shown in FIG. 3, the exhaust gas flow path 16 extends in a first direction, indicated by arrow 62, and the axis of rotation A extends in a second direction that is different than the first direction. The plane P is offset from the axis of rotation A in the first direction. In the example shown, the first and second directions are perpendicular to each other and the plane P is positioned in the exhaust gas flow path 16 at a location upstream from the axis of rotation A.

The connecting arm 22 includes a first portion 64 that is coupled to the shaft 20 and a second portion 66 that is coupled to the vane 18. In one example, the connecting arm 22 is welded to the shaft 20 and vane 18 at the first 64 and second 66 portions, respectively. The connecting arm 22 extends transversely to both the plane P and the axis of rotation A. In one example, the connecting arm 22 is perpendicular to the axis of rotation A and the plane P.

As shown in FIG. 3, the pipe body 14 extends longitudinally, i.e. along a length, to define a center axis C that coincides with a center of the exhaust gas flow path 16. In the example shown, the plane P of the vane 18 is generally parallel to, and offset from, the center axis C when the vane 18 is in the open position to provide a fully open, maximum flow, position. The offset relationship between the vane 18 and the shaft 20 provided by the transversely extending connecting arm 22 allows minimal blockage when open, i.e. maximizes the opening angle, which results in minimal backpressure.

Although an embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention. 

1. A passive valve assembly for a vehicle exhaust system comprising: an exhaust component having a wall with an inner surface defining an exhaust gas flow path; a vane positioned within the exhaust gas flow path, said vane being pivotable between an open position and a closed position, and said vane defining a plane that extends across a width of said vane; and a shaft supported by said wall and defining an axis of rotation, said shaft pivoting said vane between said open and said closed positions, and wherein said plane of said vane is offset from said axis of rotation.
 2. The passive valve assembly according to claim 1 wherein said plane does not intersect said axis of rotation.
 3. The passive valve assembly according to claim 2 wherein said plane is spaced apart from said axis of rotation by a generally constant distance as said vane pivots between said open and said closed positions.
 4. The passive valve assembly according to claim 1 wherein said exhaust gas flow path extends in a first direction and said axis of rotation extends in a second direction that is different from said first direction, and wherein said plane is offset from said axis of rotation in said first direction.
 5. The passive valve assembly according to claim 4 wherein said first direction is perpendicular to said second direction.
 6. The passive valve assembly according to claim 4 wherein said vane comprises a generally flat disc-shaped body having a greater width than thickness and wherein said plane is defined across the width of said generally flat disc-shaped body.
 7. The passive valve assembly according to 1 including a resilient member that biases said vane toward said closed position, said vane being pivoted from said closed position towards said open position in response to an exhaust gas flow that exceeds a biasing force of said resilient member.
 8. The passive valve assembly according to claim 1 wherein said exhaust component comprises a longitudinally extending pipe defining a center axis and wherein said plane of said vane is offset from, and generally parallel to, said center axis when in a fully open, maximum flow position.
 9. The passive valve assembly according to claim 1 wherein said exhaust component comprises a circular pipe defining a center axis that coincides with a center of the exhaust gas flow path, and wherein said plane of said vane and said center axis have a non-intersecting relationship when in a maximum flow position.
 10. A passive valve assembly for a vehicle exhaust system comprising: an exhaust pipe having a curved wall with an inner surface defining an exhaust gas flow path; a vane positioned within the exhaust gas flow path, said vane being pivotable between an open position and a closed position, and said vane comprising a disc-shaped body having a greater width than thickness, with said vane defining a plane that extends across said width of said disc-shaped body; and a shaft coupled to said vane and defining an axis of rotation, said shaft pivoting said vane between said open and said closed positions, and wherein said plane of said vane is offset from said axis of rotation.
 11. The passive valve assembly according to claim 10 wherein said plane has a non-intersecting relationship to said axis of rotation.
 12. The passive valve assembly according to claim 11 including a connecting arm having a first portion coupled to said shaft and a second portion coupled to said vane, said connecting arm extending transversely to said axis of rotation and said plane.
 13. The passive valve assembly according to claim 10 including a housing fixed to an outer surface of said curved wall and at least one bearing mounted within said housing to pivotally support said shaft.
 14. The passive valve assembly according to claim 13 including a resilient member that biases said vane toward said closed position, said vane being pivoted from said closed position towards said open position in response to an exhaust gas flow that exceeds a biasing force of said resilient member.
 15. The passive valve assembly according to claim 14 wherein said axis of rotation remains spaced apart from said plane by a generally constant distance as said vane moves between said open and said closed positions.
 16. The passive valve assembly according to claim 10 wherein said plane is positioned in the exhaust gas flow path at a position that is upstream relative to said axis of rotation. 